It's winter and here in Colorado, that means a cold studio. Cold clay is not only really hard on your hands, it is also prone to become brittle and crumble - not good for working at all.
So I have a really inexpensive but quite serviceable clay-warmer that you can make yourself for under $10 or quite possibly free if you have these things around your house anyway.
I took an old clip shop lamp and a 60w bulb and clipped it onto an Omaha Steaks styrofoam cooler that I got free off Craigslist. Because the cooler is deep and so insulated, it heats quickly and evenly. Even in my very cold studio. This is better than the old cooler that I had because it is deeper the light if further from the clay and the heat bounces around more so I have more even heating of the clay without melting or making it too hot to handle.
Because I use several different brands and types of oil-based clay, I try to keep the labels with the clay to avoid mixing them up.
I also need to warm the clay that is already in progress so I keep a 20 year old Black and Decker heat gun or hair dryer handy. I can warm the clay in the area that I am working and the oil-based clay will go from extremely hard and crumbly to buttery soft quite quickly. Hopefully these studio tips will help you in your sculpting.